Structural Rearrangements of Sucrose Phosphorylase from Bifidobacterium Adolescentis During Sucrose Conversion.
From: Biostructural Research Unit, Department of Medicinal Chemistry, Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
The Journal of biological chemistry
- Publish Date: Nov 2006
- ISSN: 0021-9258
- Volume: 281
- Issue: 46
- Pages: 35576-84
- Medium: Print
- Language: English
- Citation (JAMA): Mirza Osman, Skov Lars K, Sprogøe Desiree, et al. Structural Rearrangements of Sucrose Phosphorylase from Bifidobacterium Adolescentis During Sucrose Conversion.. J. Biol. Chem. Nov 2006;281:35576-84
Abstract
The reaction mechanism of sucrose phosphorylase from Bifidobacterium adolescentis (BiSP) was studied by site-directed mutagenesis and x-ray crystallography. An inactive mutant of BiSP (E232Q) was co-crystallized with sucrose. The structure revealed a substrate-binding mode comparable with that seen in other related sucrose-acting enzymes. Wild-type BiSP was also crystallized in the presence of sucrose. In the dimeric structure, a covalent glucosyl intermediate was formed in one molecule of the BiSP dimer, and after hydrolysis of the glucosyl intermediate, a beta-D-glucose product complex was formed in the other molecule. Although the overall structure of the BiSP-glucosyl intermediate complex is similar to that of the BiSP(E232Q)-sucrose complex, the glucose complex discloses major differences in loop conformations. Two loops (residues 336-344 and 132-137) in the proximity of the active site move up to 16 and 4 A, respectively. On the basis of these findings, we have suggested a reaction cycle that takes into account the large movements in the active-site entrance loops.
Mesh Headings (Keywords): Bifidobacterium, Binding Sites, Carbohydrate Conformation, Glucosyltransferases, Models, Molecular, Protein Conformation, Sucrose
Check for Full Text / PubMed Unique Identifier (PMID): 16990265
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